This invention relates to a floppy disc driving apparatus.
An apparatus for driving a floppy disc used as external memory or the like includes a disc driving mechanism for rotating a floppy disc, a head load mechanism operable in response to a drive signal to set a head in contact with the floppy disc for writing or reading data and a head positioning mechanism for setting the head in a position of a selected track. In this apparatus, if the head load mechanism operates to load upper and lower heads when a floppy disc is not set, the upper and lower heads strike to each other and may be damaged. Accordingly, a detecting circuit for checking whether a floppy disc is set or not is heretofore used. If no floppy disc is set, it provides an inhibition signal to the head load mechanism to inhibit the driving of the head to the contact position. The use of such detecting circuit, however, complicates the structure and increases the size of the driving apparatus.
Meanwhile, the floppy disc driving apparatus of this type includes an index sensor, which produces an index signal by detecting an index hole formed in the floppy disc for each rotation thereof. Successive output signals from the index sensor may be counted, and a permission signal to bring the head in contact with the floppy disc may be given to the head load mechanism when a predetermined count of output signals is reached. In this case, however, the head cannot be set in the contact position until the floppy disc has been rotated a predetermined number of rotations.